Nucleus anti-expulsion devices and methods

Abstract

Devices and methods for preventing the migration or expulsion of a nucleus disc replacement implant are provided. In one embodiment, an anti-expulsion device includes a body that is movable between a compressed configuration where it is adapted to fit through an opening in an annulus of a spinal disc, and an expanded configuration where it has a size that is larger than a size of the opening in the annulus of a spinal disc. The body can also include one or more mating features that allow the body to interact with a nucleus disc replacement implant and/or an annular wall of an annulus. As a result, since the body is larger than the opening of the annulus in the expanded configuration, the interlocking connection between the body and the nucleus disc replacement implant and/or annular wall will allow the body to prevent the nucleus disc replacement implant from being expulsed from the opening in the annulus.

What is claimed is: 
     
       1. An anti-expulsion device, comprising:
 a c-shaped body movable between a compressed configuration in which the body is adapted to fit through an opening in an annulus of a spinal disc with first and second ends of the body being moved toward one another and toward a center of the body, and an expanded configuration in which the body is configured to have a size larger than a size of the opening in the annulus of the spinal disc, and in which the first and second ends are moved away from one another and away from the center of the body, the body in the compressed configuration and in the expanded configuration including a discrete, bulbous mating feature formed on the first and second ends of the body; and 
 a nucleus disc replacement implant that encapsulates the mating feature on the body such that inside the annulus of the spinal disc the body becomes integral with the nucleus disc replacement implant to prevent expulsion of the nucleus disc replacement implant from the annulus of the spinal disc. 
 
     
     
       2. The device of  claim 1 , wherein the mating feature is selected from the group consisting of curls, hooks, undercuts, penetrating legs, staples, coils, barbs, channels, holes, claws, and combinations thereof. 
     
     
       3. The device of  claim 1 , wherein the body includes at least one bend region that facilitates movement of the body from the compressed configuration to the expanded configuration. 
     
     
       4. The device of  claim 3 , wherein the bend region is formed at a mid-portion of the body such that the first and second ends move toward one another in the compressed configuration. 
     
     
       5. The device of  claim 1 , wherein the body includes a bioactive tissue regenerative material attached thereto. 
     
     
       6. The device of  claim 1 , wherein the body is adapted to reinforce an annular wall of an annulus of a spinal disc when the body is in the expanded configuration. 
     
     
       7. The device of  claim 1 , further comprising a plug adapted to be positioned within an opening in an annulus, and wherein the body includes legs coupled to the plug and adapted to be disposed within and to engage an inner wall of an annulus. 
     
     
       8. The device of  claim 1 , wherein the c-shaped body has an S-shaped cross-sectional shape. 
     
     
       9. The device of  claim 1 , wherein the c-shaped body has a cross-sectional shape with a planar surface and a curved surface. 
     
     
       10. A nucleus disc replacement system, comprising:
 a nucleus disc replacement implant; and 
 a c-shaped anti-expulsion device having a body having a mating feature formed on first and second ends of the body, the body being movable between a compressed configuration in which the body having the c-shape and having the mating feature formed on first and second ends of the body is adapted to fit through an opening in an annulus of a spinal disc, and in which the first and second ends are moved toward a mid-portion of the anti-expulsion device, and an expanded configuration in which the body having the c-shape and having the mating feature formed on first and second ends of the body is configured to have a size larger than a size of an opening in an annulus of a spinal disc, and in which the first and second ends are moved away from the mid-portion of the anti-expulsion device, the nucleus disc replacement implant encapsulating the mating feature on the body such that following insertion of the device through the opening the device prevents expulsion of the nucleus disc replacement implant through an annulus of a spinal disc, and 
 wherein the body includes opposed legs movable between the compressed and expanded configurations, and a plug coupled to the legs and adapted to be positioned within an opening in an annulus to interlock with the annulus. 
 
     
     
       11. The system of  claim 10 , wherein the mating feature is selected from the group consisting of curls, hooks, undercuts, penetrating legs, staples, coils, barbs, channels, holes, claws, and combinations thereof. 
     
     
       12. The system of  claim 10 , wherein at least a portion of the body includes a bend region that is adapted to allow the body to move from the compressed configuration to the expanded configuration. 
     
     
       13. The system of  claim 12 , wherein the bend region is formed at the mid-portion of the body such that the first end of the body is moved toward the second end of the body when in the compressed configuration. 
     
     
       14. The system of  claim 10 , wherein the body is adapted to reinforce an annular wall of an annulus of a spinal disc when the body is in the expanded configuration. 
     
     
       15. A nucleus disc replacement system, comprising:
 a nucleus disc replacement implant; and 
 a c-shaped anti-expulsion device having a body having a mating feature formed on first and second ends of the body, the body being movable between a compressed configuration in which the body having the c-shape and having the mating feature formed on first and second ends of the body is adapted to fit through an opening in an annulus of a spinal disc, and in which the first and second ends are moved toward a mid-portion of the anti-expulsion device, and an expanded configuration in which the body having the c-shape and having the mating feature formed on first and second ends of the body is configured to have a size larger than a size of an opening in an annulus of a spinal disc, and in which the first and second ends are moved away from the mid-portion of the anti-expulsion device, the nucleus disc replacement implant encapsulating the mating feature on the body such that following insertion of the device through the opening the device prevents expulsion of the nucleus disc replacement implant through an annulus of a spinal disc wherein the body includes a tissue regenerative material attached thereto. 
 
     
     
       16. A method for implanting a nucleus disc replacement implant, comprising:
 inserting an anti-expulsion device having a mating feature formed on first and second ends of the anti-expulsion device through an opening formed in an annulus of a spinal disc to position the anti-expulsion device within a nucleus void formed in a nucleus of the spinal disc, wherein during insertion, the anti-expulsion device is in a compressed configuration in which the first and second ends are moved toward one another and toward a center of the anti-expulsion device, and in which the anti-expulsion device is c-shaped; 
 releasing a force on the anti-expulsion device such that it moves from the compressed configuration to an expanded configuration in which the first and second ends move away from one another and away from the center of the anti-expulsion device, in which the anti-expulsion device is c-shaped, and in which the anti-expulsion device having the mating feature formed on the first and second ends thereof has a size greater than a size of the opening in the annulus; and 
 inserting a nucleus disc replacement implant into the nucleus void, the nucleus disc replacement implant encapsulating the mating feature formed on first and second ends of the anti-expulsion device in the nucleus void such that the anti-expulsion device prevents expulsion of the nucleus disc replacement implant through the opening. 
 
     
     
       17. The method of  claim 16 , wherein the anti-expulsion device interlocks with the annulus. 
     
     
       18. The method of  claim 16 , wherein the anti-expulsion device is inserted through a cannula that compresses the anti-expulsion device into the compressed configuration, and wherein releasing the force comprises advancing the anti-expulsion device out of the cannula and into the nucleus void. 
     
     
       19. The method of  claim 18 , wherein the first and second ends are in contact with one another when the anti-expulsion device is in the cannula in the compressed configuration. 
     
     
       20. The method of  claim 16 , further comprising positioning the anti-expulsion device against the opening in the annulus to act as a reinforcement of an annular wall. 
     
     
       21. The method of  claim 16 , wherein the anti-expulsion device includes a tissue regenerative material, and the method further comprises positioning the anti-expulsion device against the opening in the annulus such that the tissue regenerative material facilitates regeneration of an annular wall. 
     
     
       22. The method of  claim 16 , further comprising, prior to inserting the anti-expulsion device, removing at least a portion of a nucleus from a spinal disc to form the nucleus void. 
     
     
       23. The system of  claim 10 , further comprising a cannula configured to be introduced through an opening in an annulus of a spinal disc, the body in the compressed configuration being disposed in the cannula with the first and second ends of the body moved toward one another. 
     
     
       24. The system of  claim 23 , wherein the first and second ends of the body are in contact with one another with the body in the compressed configuration within the cannula.